1. Field of the Invention
The present invention relates generally to medical instruments and more specifically to a multi-lumen catheter including y-shaped distal and proximal ends, and including selectively attachable hubs for selectively connecting the catheter to a fluid exchange device.
2. Description of the Prior Art
Catheters, generally, are hollow, flexible tubes for insertion into a body cavity, duct, or vessel to allow the passage of fluids or distend a passageway. Catheters are often used for temporary or long-term dialysis treatment. Dialysis treatment provides for blood to be withdrawn from the patient, purified, and then returned to the patient. Thus, in dialysis treatment, catheters are used to allow passage of a patient's blood into and out of the patient's body. For optimal performance during dialysis treatment, the catheter tips, both in-flow and out-flow, should be placed in close proximity to the heart. Typically, medical personnel use either a double lumen catheter or two single lumen catheters. Both types, however, present certain deficiencies.
While double lumen catheters (e.g., U.S. Pat. No. 4,895,561) allow for a single insertion of the catheter into the desired vein, double lumen catheters typically do not permit optimal catheter tip placement. Due to differences among patients, optimal top position varies from patient to patient. Non-optimal tip position may significantly lower flow values, resulting in less effective dialysis treatment. For current double lumen catheters, a physician must make an estimate regarding the appropriate catheter tube length prior to beginning the procedure of catheterization. Then, a subcutaneous tunnel is made from a first end, which is near the area to be catheterized, to a second end, which is the preferred end position of the hub assembly, namely, away from the neck of the patient, in order to allow for more convenient access to the dialysis treatment equipment. The catheter tube is then routed forwardly through the subcutaneous tunnel from the second end to the first end so that the catheter tips extend outwardly from the first end of the tunnel. Either before or after tunneling, a sheath is inserted through the first end of the tunnel and into the area to be catheterized, and the catheter tips are inserted into the sheath and the area to be catheterized. The estimated catheter tube length and subsequent forward tunneling may result in less than optimal tip placement.
With the use of two independent single lumen catheters (e.g., U.S. Pat. No. 5,776,111 to Tesio) the problem of tip placement is addressed. The hub assembly of each catheter is removable from the tube and tip portion of the catheter, thereby allowing the catheter tip to be placed directly into the vein and advanced into the desired position. Then, the proximal end of the catheter can be reverse tunneled and trimmed to a desired length. Thereafter, the hub assembly is attached. Deficiencies, however, exist in this method of catheterization as well. One problem associated with this method is that this method requires two separate venous insertions, namely, two tunnels and two of each accessory instrument used for the procedure. Therefore, there is increased surgical time required to place two catheters, there are two wound entry sites which doubles the risk of post-surgical infection, and the two catheters together are significantly larger in diameter than one double lumen catheter.
Applicant's co-pending applications Ser. No. 09/769,052 filed Jan. 24, 2001, and Ser. No. 10/086,033, filed Feb. 28, 2002, disclose a multi-lumen catheter apparatus an method for inserting the apparatus in a patient. The disclosures of these co-pending applications are hereby incorporated by reference. In the disclosed apparatus and method, a multi-lumen catheter includes a selectively attachable hub assembly that allows the catheter tip to be positioned accurately within a patient's vein prior to subcutaneous tunneling. The distal end of the catheter tube is selectively attachable to the hub assembly. Accordingly, after the tips of the catheter have been accurately positioned in a patient, the other end of the catheter may be reverse tunneled under the skin of a patient. Before or after tip placement, an incision is made in the skin adjacent to the point where the protruding distal end of the catheter exits the skin. A subcutaneous tunnel is then formed having a first end at the incision and a second end exiting the skin at a point remote from the first end of the tunnel, generally as the caudal direction. A sheath dilator is inserted into the tunnel, which is partially dilated so as to accommodate a tissue in-growth stabilizing cuff. The distal end of the catheter tube is routed through the subcutaneous tunnel and the cuff seated therein, thereby stabilizing the distal portion of the catheter tube in the patient. A selectively attachable hub assembly is connected to the lumens at the distal tip of the catheter tube for subsequent connection of the catheter to a fluid exchange device, such as a dialysis machine.
While the selectively attachable hub assembly described above facilitates tunneling a multi-lumen catheter in a patient, the separable hub assembly creates the need to connect the hub to a distal end of a multi-lumen catheter tube, thereby adding an additional step to the catheter insertion/connection procedure, which increases surgical time and expense. Furthermore, the hub-catheter connection provides an additional connection which may leak or separate from the catheter tube due to external loads on the hub such as by pulling or snagging. In addition, the attachable hub assembly is a relatively complex part, which makes it difficult to manufacture and, therefore, use of the hub assembly increases the cost of the catheter itself.
Therefore, there is a need for multi-lumen catheter that can be inserted into a patient using a reverse tunneling technique, which permits accurate placement of the tips of the catheter into the area to be catheterized and that is selectively attachable to a fluid exchange device. The improved catheter should not require an extensive hub assembly, thus making it relatively inexpensive to manufacture and easy to insert into a patient.